Recently, storage devices are required to achieve increased capacity and reduced size in order to be compatible with high-performance, compact portable equipment. In the case of a solid-state drive (SSD) serving as a storage device, a ball-grid-array-package solid-state drive (BGA-SSD), in which a nonvolatile memory and a memory controller are integrated in a single package, has been developed. Since reduced power consumption is a key factor in portable equipment, the power consumption of a storage device provided in portable equipment should be reduced as much as possible.